And then to run it you simply go to the folder containing the app.js and type:

$ spark

The output you'll see will be:

Spark server(34037) listening on http://*:3000 in development mode

Where 34037 is the process id. If you want 4 processes to balance the requests across, no problem.

$ spark -n 4

And you'll see:

Spark server(34049) listening on http://*:3000 in development mode
Spark server(34050) listening on http://*:3000 in development mode
Spark server(34052) listening on http://*:3000 in development mode
Spark server(34051) listening on http://*:3000 in development mode

MIT License

Copyright (c) 2010 Sencha Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.